Method and apparatus for the manufacture of yarn



Oct. 20, 1959 F. HESSELINK 2,908,937

METHOD AND APPARATUS FOR THE MANUFACTURE OF YARN Filed Dec. 29, 1955 Frans Hesselink,

IN V EN TOR.

2,908,937 Patented Oct. 20, 1959 United States Patent Ofiice METHOD AND APPARATUS FOR M A URE O Frans Hesselink, Arnhem, Netherlands, assignoito American Enka Corporation, Enka, N.C., a corporation of Delaware Application December 29,1955, ,Serial No. 556,256 Claims priority, application Netherlands January 11, 1955 e 1 Claims. ,(Cl. 18 -8) The present invention relates to the manufacture of rayon, and more particularly to a process and apparatus that can be utilizedefficiently in manufacturing viscose yarn wherein high spinning speeds are required.

Naturally it is more economical to produce viscose yarn at higher rates of extrusion and collection, such as, for example, above 100 meters: per minutef However, as the spinning speeds are raised, difli'culties in operating the system arise. Turbulence of the bath and frictional drag between the yarn and the bath cause inequalities in the yarn and breakage of the filaments thereof, all of which contribute to yarn of low quality.

It is known that spinning speeds can beincreased substantially by effecting motion of'the bath liquidin the same direction as that of theya rn. One such method is by positively forcing the bath liquid in the same direction, such as shown in US, Patent No., 827,434. However, by the means shown in the patent it is difiicult to properly correlate the, rate of bath travel with that of the yarn in order to minimize the friction therebetween at the point Where the freshly extrudedya'rn is most sensitive to bath turbulence, friction, drag, etc. This is because the coagulation liquid is supplied'under pressure and forced past the 'spinneret so that thefliquid carries the freshly spun yarn due to the frictionafenergy created therebetween. Moreover, it isidifiicult to maintain the proper correlation of the velocityfoff'the liquid to the thread in the first v suchcorrelationjishighly'important. This method also creates considerable complications, both with regard to control of thespinneret and the operation ofthe device.

Another method that has been'used with some degree of success, in order to utilize higher spinning speeds, is one involving passing the yarn through confined liquid treating cones such as a cylindrical tube -of' substantial length oper ted in the" manner disclosed in U.S. Patent No., 2,440,057. In that patent the freshly formed yarn is passed through the tube and the'velocity of the liquid is i correlated with that of the head in the spinbath.

Itl has now been determined that the same results can be achieved by the simple expedient of using a twodiameiger tube in which the. portion having the smaller diameter is disposed adjacent the face of the spinneret. The practical efifect of this arrangement is that after the yarn has been spun-in through the tube, it is drawn from the second, larger portion of the tube-by 1neans of agodet or the like. Under the influence of the force exercised by the go det, the yarn isjdrawn through the coagulation liquid in the second tube portion, and due to friction, the yarn carries the liquid in the same direction. The vliquid-flowing intothelarger tube portion must be replaced and consequentlyexercisesa sucking action on the liquid in thefirst smaller tube portion, so that the velocity of. the liquid in this portion is greater than the velocity in the second tube portion. The velocity in the first portion varies in direct relation to the ratio between yarn by means of the liquid portion of the spinning zone where tenacity, high denier, viscose the cross-sections .of the surfaces .of both'tube portions. It can be seenfrom this that the velocity of the liquid in .the first tube portion can be increased to the extent necessary and is most efiicient at substantially the velocity of the yarn. In this way, the yarn passes in a straight line, but under a minimum of tension, until it has been sufiiciently coagulated and regenerated to apply more tension. i 4

Of course, in order to thread the yarn through the tube during the spinning-i-n operation, a hook or other manual device can be used, but preferably a liquid head can be temporarily maintained so that the yarn is propelledby hydrostatic pressure of thec'haracter such as that shown in co-pending application Serial No. 515,146, filed June 13, 1955, now Patent No. 2,834,046 which is assigned to the same assignee as the present application.

The figure, which shows a preferred embodiment of the invention, is a diagrammatic view in elevation of the spinneret, tube and spinbath'assembly.

Referring tothe figure, there is shown a spinneret 10 mounted on a supply tube 11 which is connected to a viscose conduit, not shown, The spinneret 10 is submerged in a sulphuric acid containing spinbath 12.

A twodiameter tube 13 is mounted in supports l4 and 15 and disposed concentrically with respect to spinneret 10. As shown, the tube 13 consists of a smaller diameter section 16, a middle frusto-conical section 17, a larger diameter section 18, and is open at bothends. The'srnaller section 16 of the tube is provided with a flanged inlet end 19 adjacent the spinneret 10,, and is in the shape of a fiat trumpet.

The yarn 20 is formed of a plurality of filaments as it is drawn through the orifices in the face of 'spinneret 10, and is guided by means of roller 21 which is disposed adjacent the outlet end of the'larger, section 18 of tube 13. The yarn is 'then drawn from the bath by any suitable means, such as a godet, not shown, located beyond guide roller 22; or the guide roller 22 can be positively driven for propelling the yarn. e

The process is particularly adapted for spinning high yarn which has been prepared by adding to the viscose or the spinbath, or both, some of thewell-known regenerationretardants such as quinoline, hexamethylenediamine, mono-isopropanol, etc. In such viscoses the yarn that is formed is extremely sensitive to exterior influences near the spinneret. Therefore, by using a tube of such shape that the yarn per se can regulate the velocity of the liquid in the first part of the coagulating zone, an extremely eflicient treatment of the yarn at high speeds can be realized. By automatically raising the velocity of the liquid to substantially that of the yarn until the yarn has undergone substantial coagulationand regeneration, the yarn can be collected at substantially higher speeds and with high stretching without any detrimental effects resulting. The use of a twodiameter tube permits'such treatment wherein substantially no tension is applied to the yarn until it is sufliciently regenerated, which coincides with the so-called neutralization point. if no such provision were made for increasing the velocity of the liquid in the first part of the confined. liquid treating zone, the yarn, which is still very sensitive to mechanical. influences, will rupture easily when the velocity of the yarn is raised.

' The diameter of each portion of the tube depends on the denier of the yarn to bespun and the size of the spinnerets employed. In each case, it is a simple matter for one'skilled in the art to select the effective cross-section that corresponds with the inner diameter of the smaller tubeportion, namely, it should only slightly exceed the outer ring of spinneret orifices. (See the figure.) Then it iseasy to select the proper cross-section and length of the second larger tube portion in such a way that the 3 coagulation liquid in the first tube portion moves at substantially the same velocity as the yarn, which prevents the liquid from exercising any detrimental mechanical action on the yarn. The frusto-conical portion connects the smaller and larger sections at a gradual taper, 7

In order to achieve the most favorable results, it is desirable, although not essential, to observe several further precautions. The inner diameter of the smaller portion of the spinning tube is preferably 20-40% larger than that of the outer ring of the spinneret orifices. Furthermore, in order to avoid turbulence to the maximum extent, the inlet opening is in the shape of a short flat trumpet and is disposed concentrically as close as possible 1 to the spinneret. In order to minimize turbulence at the transition between the narrow and wide tube sections, it is preferable to gradually taper the frusto-conical portion whereby the sucking action obtains a maximum value and the filaments of the yarn spread uniformly throughout the interior of the tube.

In the manufacture of viscose rayon having 80-120 denier, the outer ring of spinneret orifices has, for example, a diameter of about 9 mm., in which case the smaller tube portion should be about 10-12 mm. The inner diameter of the wide tube portion should be about 1.2 to 1.5 times larger than the narrow tube portion. It has been determined that the length of the wide tube portion should be 25-40 cm. in order to exercise a satisfactory sucking action. With respect to the middle frustoconical portion, it has been found that its length should, at most, be twice that of the inner diameter of the wide tube portion.

For the manufacture of yarns having high denier, for

. 4 stretching was effected in a second bath at 90 C. contain ing 3% by weight of H 80 The threads thus obtained had a denier of 1815, the dry strength was 392 g./ 100 denier and the dry elongation was 22.8%. When no tube was used, spinning at the aforesaid speed proved tobe'impossible owing to frequent yarn ruptures.

What is claimed is:

1. In apparatus for the manufacture of rayon including a spinneret to extrude a spinning solution into an acid coagulating bath to form yarn therefrom and means to withdraw the yarn from the bath at a higher velocity than the rate of extrusion, the improvement which comprises a spinning tube mounted concentric with the spinneret, said spinning tube having two cylindrical tube sections of different diameters connected intermediate the ends thereof by a frusto-conical section, the smaller tube section being slightly larger than the diameter of the example, 1600 denier, for use in making tire cord, the I diameter of the outer ring of spinneret orifices is usually about 16 mm., in which case, the inner diameter of the narrow tube portion should be approximately 20-22 mm.

At a primary yarn velocity of m./min. and a velocity after stretching of 60 m./min., a tube may be satisfactory which has a narrow tube portion length of 30 cm., and a diameter of 21 mm. The second portion has a length of 20 cm. and a diameter of 27 mm. The frusto-conical portion has a length of 5 cm.

.As stated before, the inlet opening of the narrow tube portion is preferably provided with a flat trumpet-shaped flange, and is placed as close as possible to the spinneret face without inhibiting the free flow of coagulation liquid into the tube or causing a turbulence. The correct spacing is determined by the denier of the yarn, the diameter of the spinneret face, and the spinning velocity. As a rule it is preferred to space the inlet opening a distance of 5-20 mm. from the face of the spinneret.

Example A viscose solution was prepared from cotton linters having a cellulose content of 7.7% by weight, an alkali content of 5.5% by weight, a xanthate ratio of 0.47 and a ball fall viscosity of 60 sec., to which 0.16% by weight of quinoline was added. It was spun, by means of the system described above, in a spinbath maintained at 60 C. containing 6% by weight of sulphuric acid, 19% by weight of sodium sulphate and 3.8% by weight of zinc sulphate. In the spinning operation a gold-platinum spinneret was used in which 1060 orifices each having a diameter of 60 micron had been drilled. The diameter of the outer ring of spinning orifices was 16 mm.. ,The narrower tube portion had an inner diameter of 21 mm., the wider tube portion an inner diameter of 27 mm., the length of the narrow tube portion being 30 cm. and that of the wider tube portion 19 cm. The length of the frustoconical portionbetween these two portions was 4 cm. long. The outer diameter of the trumpet-shaped inlet opening was 4 cm. This inlet opening was situated at a distance of 2 cm. from the spinneret. The primary drawing-01f speed was m./min. and the winding-up speed was 80 m./min., the resulting stretch being 100%. This spinneret and disposed adjacent thereto-with the larger tube section at the end remote from the spinneret, said yarn withdrawal means creating frictional drag between the yarn and liquid in the larger tube section thereby increasing the velocity of the liquid relative to the yarn in the smaller tube section, the construction and arrangement of said tube being such that the movement of the liquid through said tube sections is effected substantially solely by said frictional drag between the yarn and the liquid.

2. Apparatus according to claim 1 in which the smaller tube section is 2040% larger than the outer ring of spinneret orifices.

3. Apparatus according to claim 2 in which the inlet end of the smaller tube section is provided with a flange in the shape of a flat trumpet.

4. Apparatus according to claim 3 in which the inlet end of the smaller tube section is disposed 5-20 mm. from the face of the spinneret.

5. In apparatus for the manufacture of rayon including a spinneret to extrude a spinning solution into an acid coagulating bath to form yarn therefrom and means to withdraw the yarn from the bath at a higher velocity than the rate of extrusion, the improvement which comprises a spinning tube mounted concentrically 5-20 mm. from the face of the spinneret, said tube consisting of two cylindrical sections of different diameters connected by a gradually tapering section intermediate the ends of said spinning tube, the inlet end of the smaller tube section being nearer the spinneret than the larger tube section and the inner diameter of the larger tube section being 1.21.5 times greater than the inner diameter of the smaller tube section.

6. In a method of producing yarn in which a viscose the yarn is withdrawn from the bath at a substantially higher velocity than the rate of extrusion, the improvement which comprises extruding the yarn into the bath and passing each individual yarn through an adjacent cylindrical concentrically disposed confined liquid treating zone that completely surrounds the yarn and is only slightly greater in cross section than the cross section of the outer ring of said spinneret orifices, positively drawing the yarn through an adjacent cylindrical concentrically confined liquid treating zone that is greater in cross section than the said first zone, at a velocity that induces the liquid in said first zone to flow concurrently with the freshly formed yarn solely from the frictional drag created between the yarn and the liquid in the contiguous zone.

7. In a method of producing yarn in which a viscose solution is extruded through circularly arranged fine spinneret orifices into an aqueous sulphuric acid coagulating bath to form a continuous filament yarn therefrom and the yarn is withdrawn from the bath at a substantially higher velocity than the rate of extrusion, the improvement which comprises extruding the yarn into the bath and passing each individual yarn through an adjacent cylindrical concentrically disposed confined liquid treating zone that completely surrounds the yarn and is only slightly greater in cross section than the cross section of the outer ring of said spinneret orifices, positively drawing the yarn through an adjacent cylindrical concentrically confined liquid treating zone that is greater in cross section than the said first zone, at a velocity that induces the liquid in said first zone to flow concurrently with the freshly formed yarn at substantially the same velocity as the yarn solely from the frictional drag created between the yarn and the liquid in the contiguous zone.

References Cited in the file of this patent UNITED STATES PATENTS 

1. IN APPARATUS FOR THE MANUFACTURE OF RAYON INCLUDING A SPINNERET TO EXTRUDE A SPINNING SOLUTION INTO AN ACID COAGULATING BATH TO FORM YARN THEREFROM AND MEANS TO WITHDRAW THE YARN FROM THE BATH AT A HIGHER VELOCITY THAN THE RATE OF EXTRUSION, THE IMPROVEMENT WHICH COMPRISES A SPINNING TUBE MOUNTED CONCENTRIC WITH THE SPINNERET, SAID SPINNING TUBE HAVING TWO CYLINDRICAL TUBE SECTIONS OF DIFFERENT DIAMETERS CONNECTED INTERMEDIATE THE ENDS THEREOF BY A FRUSTO-CONICAL SECTION, THE SMALLER TUBE SECTION BEING SLIGHTLY LARGER THAN THE DIAMETER OF THE SPINNERET AND DISPOSED ADJACENT THERETO WITH THE LARGER 